WASHINGTON (Reuters) - Officials at Guantanamo Bay prison are using force feedings of a Syrian detainee to discourage other inmates from joining a hunger strike, a witness at a federal trial over his treatment said on Tuesday.

The prisoner, Abu Wa'el Dhiab, 43, has been held at the prison in Cuba without charges for 12 years. He was cleared for release in 2009 but the process has stalled as the United States looks for another country to take him.

He has been on a hunger strike and Dhiab's lawyers have said the practice of forcibly removing him from his cell, restraining him and feeding him through a nasal tube up to twice a day was illegal and abusive.

The prison is using unnecessarily frequent feedings as a "punitive strategy" to discourage hunger striking, Dr. Steven Miles, a professor of medicine at the University of Minnesota and an expert on tube feeding, testified during a hearing in U.S. District Court in Washington.

"There was no indication of malnutrition when they began the force feedings," he said, adding that the prison has failed to provide Dhiab proper medical care.

Miles said that Dhiab, who is 6 feet 5 inches (1.95 m) tall and weighed 152 pounds (69 kg) as of last week, was at a "baseline" weight.

According to a military spokesman, Dhiab is among more than 100 detainees who have gone on a hunger strike.

Miles also criticized prison staff for using olive oil to lubricate the feeding tubes. He called it an "astonishing" practice that could lead to a rare form of pneumonia, fibrosis and long-lasting harm.

Dhiab's lawyers are seeking a court order that would make the force feedings more humane by allowing Dhiab to use a wheelchair instead of being forcibly removed from his cell by guards.

They have also asked that a doctor assess their client before each force feeding to confirm that his health is in danger, among other requests.

According to medical records presented on Monday, Dhiab has suffered from nose bleeds, chronic back pain, blood in his urine and other medical problems.

On Friday, U.S. District Judge Gladys Kessler ordered the U.S. government to prepare public versions of 28 videos that show Dhiab being force fed.

The ruling came after media organizations filed a motion to have the footage released.